He told the BBC's Politics Show in Scotland: "I have asked the Labour Party's lawyers to look at the prospects of a legal challenge, and that is currently underway.

"If the legal advice which emanates from the Labour Party's solicitors is that there is a prospect of a challenge and that challenge goes ahead then yes, I would have the backing of the local Labour Party.

"It would be the local Labour Party who would determine that, nobody else."

He said any challenge would be funded by the local party's indemnity insurance.

First Minister Jack McConnell said he did not want to comment on the situation in Cunninghame North.

Spoiled papers

"If there is to be a challenge at the local level in any constituency it would be a matter for the local candidate and agent," he told BBC Radio Scotland's Sunday Live programme.

"They themselves need to take the decision about whether to pursue a challenge."

Up to 100,000 ballot papers were counted as spoiled across Scotland in the election.

Mike Dailly from the Govan Law Centre told BBC Scotland that these people had been "denied democracy".

Mike Dailly suggested two ways forward

He said there had been about 10,000 spoiled ballots on the regional list in Glasgow.

"If a few hundred of those had gone to Tommy Sheridan he would have been elected," said Mr Dailly.

"If perhaps some more went to the Greens we would have had another Green MSP, so it is that important."

He suggested two possible ways forward in Glasgow.

"Either we re-run the election or the returning officer contacts these 10,000 people who had their ballot treated as spoiled to ascertain their actual preference.

"We need to do that, otherwise democracy is in crisis in Scotland."

I am not sure that anybody in Scotland now wants to see a protracted legal challenge

Nicola SturgeonSNP deputy leader

Labour finished with 46 seats in the 129-member Scottish Parliament. Alex Salmond's Scottish National Party narrowly emerged as the largest group with 47.

Labour's Allan Wilson lost Cunninghame North to SNP candidate Kenneth Gibson by just 48 votes.

SNP deputy leader Nicola Sturgeon said the number of spoiled ballot papers was "extremely regrettable".

However, she said she did not think that the problems affected any one party more than another.

"That's why I don't believe there is a real grounds for suggesting that the results would have been different had these ballots been counted," she said.

And she added: "I am not sure that anybody in Scotland now wants to see a protracted legal challenge."